package bit_0530_0313;

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;

public class T7_0313 {
    static class TreeNode {
        public char val;
        public TreeNode left;//左孩子的引用
        public TreeNode right;//右孩子的引用

        public TreeNode(char val) {
            this.val = val;
        }
    }


    /**
     * 创建一棵二叉树 返回这棵树的根节点
     *
     * @return
     */
    public static TreeNode createTree() {
        TreeNode A = new TreeNode('A');
        TreeNode B = new TreeNode('B');
        TreeNode C = new TreeNode('C');
        TreeNode D = new TreeNode('D');
        TreeNode E = new TreeNode('E');
        TreeNode F = new TreeNode('F');
        TreeNode G = new TreeNode('G');
        TreeNode H = new TreeNode('H');
        A.left = B;
        A.right = C;
        B.left = D;
        B.right = E;
        E.right = H;
        C.left = F;
        C.right = G;
        return A;
    }

    // 前序遍历
    public static void preOrder(TreeNode root) {
        if (root == null) {
            return;
        }
        System.out.print(root.val + " ");
        preOrder(root.left);
        preOrder(root.right);
    }

    // 中序遍历
    static void inOrder(TreeNode root) {
        if (root == null) {
            return;
        }
        inOrder(root.left);
        System.out.print(root.val + " ");
        inOrder(root.right);
    }

    // 后序遍历
    static void postOrder(TreeNode root) {
        if (root == null) {
            return;
        }
        postOrder(root.left);
        postOrder(root.right);
        System.out.print(root.val + " ");
    }

    public static int nodeSize;

    /**
     * 获取树中节点的个数：遍历思路
     */
    static void size(TreeNode root) {
        if (root == null) {
            return;
        }
        nodeSize++;
        size(root.left);
        size(root.right);
    }

    /**
     * 获取节点的个数：子问题的思路
     *
     * @param root
     * @return
     */
    static int size2(TreeNode root) {
        if (root == null) {
            return 0;
        }
        return 1 + size2(root.left) + size2(root.right);
    }


    /*
     获取叶子节点的个数：遍历思路
     */
    public static int leafSize = 0;

    static void getLeafNodeCount1(TreeNode root) {
        if (root == null) return;
        if (root.left == null && root.right == null) {
            leafSize++;
            return;
        }
        getLeafNodeCount1(root.left);
        getLeafNodeCount1(root.right);
    }

    /*
     获取叶子节点的个数：子问题
     */
    static int getLeafNodeCount2(TreeNode root) {
        if (root == null) return 0;
        if (root.left == null && root.right == null) {
            return 1;
        }
        return getLeafNodeCount2(root.left) + getLeafNodeCount2(root.right);
    }

    /*
    获取第K层节点的个数
     */
    static int getKLevelNodeCount(TreeNode root, int k) {
        if (root == null) return 0;
        if (k == 1) return 1;
        return getKLevelNodeCount(root.left,k - 1) + getKLevelNodeCount(root.right,k - 1);
    }

    /*
     获取二叉树的高度
     时间复杂度：O(N)
     */
    static int getHeight(TreeNode root) {
        if (root == null) return 0;
        if (root.left == null && root.right == null) return 1;
        int leftheight = getHeight(root.left);
        int rightheight = getHeight(root.right);
        return Math.max(leftheight, rightheight) + 1;
    }


    // 检测值为value的元素是否存在
    static TreeNode find(TreeNode root, char val) {
        if (root == null) return null;
        if (root.val == val) return root;
        TreeNode left = find(root.left,val);
        TreeNode right = find(root.right,val);
        return left != null ? left : right;
    }

    //层序遍历
    static void levelOrder(TreeNode root) {
        if (root == null) {
            return;
        }
        Queue<TreeNode> que = new LinkedList<>();
        que.offer(root);
        while (!que.isEmpty()) {
            TreeNode tmp = que.poll();
            System.out.print(tmp.val + " ");
            if (tmp.left != null) {
                que.offer(tmp.left);
            }
            if (tmp.right != null) {
                que.offer(tmp.right);
            }
        }
    }
    static List<List<TreeNode>> levelOrder2(TreeNode root) {
        if (root == null) {
            return null;
        }
        List<List<TreeNode>> list = new ArrayList<>();
        Queue<TreeNode> que = new LinkedList<>();
        que.offer(root);
        while (!que.isEmpty()) {
            int size = que.size();
            List<TreeNode> treeNodeList = new ArrayList<>();
            while (size != 0) {
                TreeNode tmp = que.poll();
                treeNodeList.add(tmp);
                size--;
                System.out.print(tmp.val + " ");
                if (tmp.left != null) {
                    que.offer(tmp.left);
                }
                if (tmp.right != null) {
                    que.offer(tmp.right);
                }
            }
            list.add(treeNodeList);
        }
        return list;
    }

    // 判断一棵树是不是完全二叉树
    static boolean isCompleteTree(TreeNode root) {
        if (root == null) return true;
        Queue<TreeNode> queue = new LinkedList<>();
        queue.offer(root);
        while (!queue.isEmpty()) {
            TreeNode tmp = queue.poll();
            if (tmp != null) {
                queue.offer(tmp.left);
                queue.offer(tmp.right);
            } else {
                break;
            }
        }
        while (!queue.isEmpty()) {
            TreeNode cur = queue.poll();
            if (cur == null) {
                return false;
            }
        }
        return true;
    }

    public static void main(String[] args) {
        TreeNode root = createTree();
        preOrder(root);
        System.out.println();
        inOrder(root);
        System.out.println();
        postOrder(root);
        System.out.println();
        size(root);
//        System.out.println(nodeSize);
//        System.out.println(size2(root));
//        getLeafNodeCount1(root);
//        System.out.println(leafSize);
//        System.out.println(getLeafNodeCount2(root));
//        System.out.println(getKLevelNodeCount(root,3));
//        System.out.println(getHeight(root));
//        if(find(root,'M') != null) {
//            System.out.println(find(root, 'B').val);
//        }
//        levelOrder(root);
//        System.out.println();
//        System.out.println(isCompleteTree(root));
    }
}
